Hello,
CUDA was discussed before, check the archives.
Best regards,
Tomasz Janeczko
amibroker.com
On 2010-08-22 21:52, TA wrote:
Thanks again. My last question. Have you tested AB to hand over some calculations to GPU (e.g., using CUDA)? Since GPU has its own FPU and memory. Sorry for
all these layman question! I am really fascinated by all these stuff. TIA
*From:* [email protected] [mailto:[email protected]] *On Behalf
Of *Tomasz Janeczko
*Sent:* Sunday, August 22, 2010 12:30 PM
*To:* [email protected]
*Subject:* Re: [amibroker] OT: mutlicore cpu
Hello,
"why you bought an i7 (6 core) cpu?"
Several reasons - my previous computer was 4 year old and it was 2 core. Buying anything less than i7 would not give me any visible gain. In, although new
machine is faster, in everyday tasks it makes little difference (especially with the fact that Windows and other softwares add bloat faster than hardware
evolves.) As to technical reasons - among other things - to do actual tests. 4 years ago I have written portions of AFL engine using OpenMP (parallel library)
to test actual, real-world performance of parallel (multi-core) code vs single-core on AMD Athlon64x2 (2core) Last year, I bought i7 to re-run those tests on
latest hardware. The conclusion is the same, fine-grain parallelism (the one that OpenMP supports) with 3:1 memory to FPU ratio makes no sense
performance-wise. You need much more FPU/CPU calcs per single memory access to make it worthwhile.
With regards to buying new hardware: If you develop software, you need to have several platforms to test on to ensure smooth operation on every popular
hardware. I am testing AmiBroker on everything starting from Intel Celeron 600MHz (10-year old notebook), AMD Athlon XP (single core), AMD Athlon64x2 (dual
core), Intel Core 2 Duo (2 core), and ending with Intel i7 920 (6core).
Best regards,
Tomasz Janeczko
amibroker.com
On 2010-08-22 20:43, TA wrote:
Thanks for clarification. Would you mind sharing with us why you bought an
i7 (6 core) cpu? TIA
*From:* [email protected] <mailto:[email protected]>
[mailto:[email protected]] *On Behalf Of *Tomasz Janeczko
*Sent:* Sunday, August 22, 2010 11:24 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [amibroker] OT: mutlicore cpu
Hello,
Video creation software is completely different. They do a lot of math *per
pixel* (it means that lots of FPU operations are needed for single pixel), for
example many algorithms use 8x8 pixel blocks 64*(4 bytes per pixel)=
256bytes and do complex transform such as cosine transform. It means that lots
of FPU
instructions are done on very small blocks of memory that completely fit on
Level 1 CPU cache and thus they are not able to saturate memory bandwidth.
They literally do dozens of FPU ops per single RAM access. In fact they
barely need to touch RAM at all. It is completely opposite to how AFL works,
where
there is usually 3 times more memory accesses (2 reads + one write) than
FPU operations.
And yes I do know what processors are on the market. In fact I do have i7
(6 core) (I am writing this post using it).
The only reason for multi threading in case of AFL would be not speed but
asynchronous/parallel execution (ability to run AFL that takes long time in
parallel
(without blocking) other AFLs).
Best regards,
Tomasz Janeczko
amibroker.com
On 2010-08-22 01:19, TA wrote:
TJ
On many occasions you have written that the reason that you have not
implement multicore usage in AB is that single symbol data saturates the on-die
cache and memory bandwidth. The tests that I have seen for video
creation shows the apps that take advantage of multicore processes finish the
tasks
faster. Do you know why that is? Do you know why AMD & Intel are
creating six core cpus (soon 8 core cpus)?TIA
